https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:44996 Batrachochytrium dendrobatidis is an emerging infectious pathogen present on every continent except Antarctica. It causes the disease chytridiomycosis in a subset of species but does not always result in disease or death for every host. Ambient temperature influences both amphibian metabolism and chytrid pathogenicity, however the interactive effects on host physiology is not well understood. We investigated the sublethal effect of B. dendrobatidis infection on a susceptible host, Litoria aurea to test (1) whether the infection load, metabolic activity, body fat and gonad size differed in L. aurea at either 24 °C or 12 °C ambient temperatures and (2) whether previous Bd infection caused long-term changes to body fat and gonad size. Litoria aurea in 12 °C treatments had higher infection loads of B. dendrobatidis and lower survivorship. Metabolic rate was higher and fat mass was lower in infected individuals and in animals in 24 °C treatments. Male L. aurea previously infected with B. dendrobatidis had smaller testes 5 months-post clearance of infection, an effect likely to translate to fitness costs in wild populations. These experiments demonstrate a physiological cost to sublethal B. dendrobatidis infection, which suggests a reduction in host fitness mediated by temperature in the host’s environment regardless of whether infection leads to mortality.]]> Wed 26 Oct 2022 09:28:56 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:48961 Wed 19 Apr 2023 12:34:46 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19056 Wed 11 Apr 2018 15:45:47 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29348 Wed 11 Apr 2018 11:27:40 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:33311 Litoria aurea were placed in water collected from ponds that were used by this species for breeding and ponds where breeding was not detected at Sydney Olympic Park, Australia. After 19 days, the tadpoles were placed in enclosures in the same breeding and non‐breeding ponds, and monitored until they metamorphosed. There was no difference in tadpole survival, time to metamorphosis or body condition between the two treatments, indicating that poor water quality was not a cause of low pond occupancy by tadpoles at the site and resources should be directed towards investigating other potential causes. We suggest that this method of an ex situ followed by an in situ exposure study is an effective approach to eliminating or confirming poor water quality as a cause of population declines and reduced occupancy, for species that are aquatic for at least part of their life cycle. Other applications include establishing that artificially created habitat provides suitable water chemistry, or identifying a potential location for a reintroduction project.]]> Wed 10 Oct 2018 12:10:24 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:50162 50% chance) of becoming extinct by 2040, with the disease chytridiomycosis identified as the primary threat. A further five species are at moderate–high risk (30–50% chance), primarily due to climate change. Fourteen of the 26 frog species are endemic to Queensland, with many species restricted to small geographic ranges that are susceptible to stochastic events (e.g. a severe heatwave or a large bushfire). Experts were more likely to rate extinction probability higher for poorly known species (those with <10 experts), while non-experts were more likely to rate extinction probability higher for better-known species. However, scores converged following discussion, indicating that there was greater consensus in the estimates of extinction probability. Increased resourcing and management intervention are urgently needed to avert future extinctions of Australia’s frogs. Key priorities include developing and supporting captive management and establishing or extending in-situ population refuges to alleviate the impacts of disease and climate change.]]> Wed 05 Jul 2023 16:03:34 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:35823 Batrachochytrium dendrobatidis (chytrid) has caused the most widespread, disease-induced declines and extinctions in vertebrates recorded to date. The largest climatically suitable landmass that may still be free of this fungus is New Guinea. The island is home to a sizeable proportion of the world's known frog species (an estimated 6%), as well as many additional, yet-to-be-described species. Two decades of research on the chytrid fungus have provided a foundation for improved management of amphibian populations. We call for urgent, unified, international, multidisciplinary action to prepare for the arrival of B dendrobatidis in New Guinea, to prevent or slow its spread within the island after it arrives, and to limit its impact upon the island's frog populations. The apparent absence of the fungus in New Guinea offers an opportunity to build capacity in advance for science, disease surveillance, and diagnosis that will have broad relevance both for non-human animal health and for public health.]]> Tue 10 Dec 2019 11:18:28 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:26207 Thu 19 Aug 2021 10:51:41 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19514 Sat 24 Mar 2018 08:02:07 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20082 Sat 24 Mar 2018 08:00:08 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20083 Sat 24 Mar 2018 08:00:05 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:20281 Sat 24 Mar 2018 07:59:54 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29688 Batrachochytrium dendrobatidis limits population recovery and conservation actions for threatened amphibians. As such, the effect of reservoirs on disease risk within host community assemblages needs to be considered, but rarely is. Aims: In this study we aimed to determine if amphibian species co-occurring with the green and golden bell frog Litoria aurea, a declining species susceptible to B. dendrobatidis, act as alternate hosts. Methods: We quantified B. dendrobatidis infection levels, sub-lethal effects on body condition and terminal signs of disease in amphibian communities on Kooragang Island and Sydney Olympic Park in New South Wales, Australia, where two of the largest remaining L. aurea populations persist. Key results: We found L. aurea carried infections at a similar prevalence (6–38%) to alternate species. Infection loads ranged widely (0.01–11 107.3 zoospore equivalents) and L. aurea differed from only one alternate host species (higher median load in Litoria fallax) at one site. There were no terminal or sub-lethal signs of disease in any species co-occurring with L. aurea. Conclusion: Our results suggest that co-occurring species are acting as alternate hosts to L. aurea and whether their presence dilutes or amplifies B. dendrobatidis in the community is a priority for future research. Implications: For L. aurea and many other susceptible species, confirming the existence of reservoir hosts and understanding their role in community disease dynamics will be important for optimising the outcomes of threat mitigation and habitat creation initiatives for their long-term conservation.]]> Sat 24 Mar 2018 07:38:49 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30290 Batrachochytrium dendrobatidis (Bd) infection has led to the decline of many amphibian species. Despite increasing knowledge on how Bd varies in its effects among species, little is known on the interaction between susceptibility and development within host species. We compared the ontogenetic susceptibility of post-metamorphic green and golden bell frogs Litoria aurea to chytridiomycosis by simultaneously measuring three host-pathogen responses as indicators of the development of the fungus—infection load, survival rate, and host immunocompetence—following Bd exposure in three life stages (recently metamorphosed juveniles, subadults, adults) over 95 days. Frogs exposed to Bd as recently metamorphosed juveniles acquired higher infection loads and experienced lower immune function and lower survivorship than subadults and adults, indicating an ontogenetic decline in chytridiomycosis susceptibility. By corresponding with an intrinsic developmental maturation in immunocompetence seen in uninfected frogs, we suggest these developmental changes in host susceptibility in L. aurea may be immune mediated. Consequently, the physiological relationship between ontogeny and immunity may affect host population structure and demography through variation in life stage survival, and understanding this can shape management targets for effective amphibian conservation.]]> Sat 24 Mar 2018 07:33:34 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28845 litoria aurea, l. castanea, and l. raniformis. there is considerable debate about the role of threatening processes in the decline and uncertainty in how best to develop conservation mitigation strategies for these species. to develop a clear picture of the research priorities necessary to enhance the conservation outcomes for the three species we conducted a literature review to focus on the critical gaps in ecological understanding that prevents consensus, and to set research priorities to address these gaps. Unresolved questions were identified and prioritized, and a set of priority research directions and management actions considered to be integral for the persistence of the species were formulated.]]> Sat 24 Mar 2018 07:33:21 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29797 Batrachochytrium dendrobatidis, a pathogen that can cause the fatal disease chytridiomycosis. We measured the infection load and observed signs of disease in Litoria aurea. Receiver operating characteristic curves were used to quantify the dissimilarity between the infection loads of L. aurea that showed signs associated with chytridiomycosis and those that did not. Litoria aurea had a 78% probability of developing chytridiomycosis past a threshold of 68 zoospore equivalents (ZE) per swab and chytridiomycosis occurred within a variable range of 0.5–490 ZE. Studies should incorporate a species-specific threshold as a predictor of chytridiomycosis, rather than a binary diagnosis. Measures of susceptibility to chytridiomycosis must account not only for the ability of B. dendrobatidis to increase its abundance on the skin of amphibians but also to determine how each species tolerates these infection loads.]]> Sat 24 Mar 2018 07:30:36 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:26628 Batrachochytrium dendrobatidis has been a major contributing factor to the global decline of amphibians. Knowledge of the distribution of B. dendrobatidis can contribute to understanding patterns of species decline and prioritizing action. Therefore, we surveyed four spatially distinct populations of a B. dendrobatidis susceptible species, the green and golden bell frog (Litoria aurea), for evidence of infection in the population. Three mainland populations were infected at a prevalence of 3.5-28.3 %, with median infection loads of 0.28-627.18 genomic equivalents (GE). Conversely, we did not detect infection in an island population 3 km from the mainland; the isolation and infrequent visitation of the island suggests that the pathogen has not arrived. Management actions for B. dendrobatidis and conservation of susceptible frog species are heavily dependent on the presence and absence of the pathogen in the population. Prevention of the accidental introduction of B. dendrobatidis and safe guarding genetic diversity of L. aurea is necessary to preserve unique diversity of the island population, whereas containment and control of the pathogen can be directed towards mainland populations. Knowledge of disease dynamics also provides a context to understand the ecology of remaining populations as variation in the physiology or habitat of the mainland populations have facilitated persistence of these populations alongside B. dendrobatidis. Other islands should be a priority target in disease surveillance, to discover refuges that can assist conservation.]]> Sat 24 Mar 2018 07:26:48 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30517 Litoria aurea) and the introduced eastern gambusia (Gambusia holbrooki) in Sydney, Australia. From 2003 to 2012 we drained ponds to temporarily remove gambusia and examined the effect of removal on the numbers of male, female, and juvenile frogs, and tadpoles. We found that males preferentially selected fish-free ponds as breeding sites. In addition, the removal of gambusia increased tadpole abundance to over 140 times that of an undrained pond. Pond draining did not influence female or juvenile abundances. The ability to detect and avoid gambusia may be mitigating the effect of predation to a certain extent. We conclude that pond draining to remove exotic fish is an effective strategy that can be used to greatly increase the reproductive success of this and potentially other threatened amphibian species in the presence of exotic predators.]]> Sat 24 Mar 2018 07:25:07 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:23886 Litoria aurea) using radio tracking methods during winter when detection is low and knowledge is limited. We followed 26 individuals between May and July, 2011 to determine whether they selected specific overwintering microhabitats and related this to levels of individual exposure to predators, distance from the edge of the water and temperature of microhabitats. We found that overwintering bell frogs inhabited reeds and rock gabions more frequently than expected and that females used a reduced subset of microhabitats compared to males. Additionally, microhabitats used were more likely to conceal an individual from view, and the majority of overwintering sites were located within 5m of the edge of the water which may be important for reducing the risk of predation and desiccation. Rock gabions had significantly warmer (1.2°C-1.8°C) mean temperatures than the other microhabitats used. The information presented here can be used in habitat creation and reintroduction programmes to provide habitat which is suitable during both the breeding and non-breeding season for the conservation of other populations.]]> Sat 24 Mar 2018 07:13:40 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:48197  1,050 fire-affected taxa, we selected 173 whose distributions substantially overlapped the fire extent. We estimated the proportion of each taxon’s distribution affected by fires, using fire severity and aquatic impact mapping, and new distribution mapping. Using expert elicitation informed by evidence of responses to previous wildfires, we estimated local population responses to fires of varying severity. We combined the spatial and elicitation data to estimate overall population loss and recovery trajectories, and thus indicate potential eligibility for listing as threatened, or uplisting, under Australian legislation. Results: We estimate that the 2019–2020 Australian megafires caused, or contributed to, population declines that make 70–82 taxa eligible for listing as threatened; and another 21–27 taxa eligible for uplisting. If so-listed, this represents a 22–26% increase in Australian statutory lists of threatened terrestrial and freshwater vertebrates and spiny crayfish, and uplisting for 8–10% of threatened taxa. Such changes would cause an abrupt worsening of underlying trajectories in vertebrates, as measured by Red List Indices. We predict that 54–88% of 173 assessed taxa will not recover to pre-fire population size within 10 years/three generations. Main conclusions: We suggest the 2019–2020 Australian megafires have worsened the conservation prospects for many species. Of the 91 taxa recommended for listing/uplisting consideration, 84 are now under formal review through national processes. Improving predictions about taxon vulnerability with empirical data on population responses, reducing the likelihood of future catastrophic events and mitigating their impacts on biodiversity, are critical.]]> Sat 11 Mar 2023 12:30:03 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:51249 Mon 28 Aug 2023 12:29:36 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:39722 Batrachochytrium dendrobatidis, is one of the most widespread and damaging pathogens to biodiversity. New Guinea hosts 6% of the world's frogs and is the largest landmass where B. dendrobatidis remains undetected despite being largely climatically suitable for its persistence. We surveyed for B. dendrobatidis in Papua New Guinea, by swabbing live frogs in the Gulf Province and Eastern Highlands Province and by examining museum specimens from a range of sites and elevations. Here, we show that over a large geographical range, all 442 samples were negative for B. dendrobatidis. The spread of B. dendrobatidis to Papua New Guinea may have been thus far prevented by the remoteness of New Guinea and the hotter climate in its lowlands, which surrounds a more climatically suitable zone for B. dendrobatidis in the highlands. Alternatively, B. dendrobatidis may be present in isolated patches or at low levels and remain undetected, to date. Papua New Guinea remains at risk and would benefit from a national disease surveillance program for chytrid fungi and pre-emptive actions, designed to reduce the risk of pathogen transmission. Measures should include improved biosecurity protocols for trade and travel and continued disease surveillance in areas of probable entry and spread.]]> Fri 17 Jun 2022 17:38:03 AEST ]]>